Odd flies

There are plenty of flies, as well as bees, buzzing the garden flowers these days. Macro close-ups of some of them reveal some interesting features.

At first I thought this was a horse fly with pollen on its legs.  Looking closer however, it seems to have yellow feet at the terminus of each of its legs.

At first I thought this was a horse fly with pollen on its legs. Looking closer however, it seems to have yellow feet at the terminus of each of its legs.  So I googled “yellow-footed fly”, and a photo of a Tachinid fly (Tachina species) on BugGuide.net came right up.

Tachinid flies are parasites (coexist inside the host) or parasitoids (use the host’s body for development, ultimately killing it) on a multitude of host species:  beetles and beetle larvae, butterfly and moth caterpillars, true bugs, grasshoppers, even other flies.

In addition to his yellow feet, this fly has a yellow face and yellow patches right at the base of the wing.

In addition to his yellow feet, this fly has a yellow face and yellow patches right at the base of the wing.  Forelegs together, cleaning his proboscis before moving on.

Specialized ovipositors enable the female to pierce the cuticle of potential hosts to insert her egg; the larva hatches within a few days to immediately begin consuming organs of the host.  Some Tachinid fly species lay their eggs on the plants consumed by the host so that eggs are ingested and then hatch in the digestive organs of the host.  Sounds gruesome, but these flies are actually good bio-control agents for some insect pest species.  In addition, the adults which feed on nectar, are pretty effective pollinators for many plant species.

Picture-winged flies have a peculiar way of sitting at rest with their wings spread out, slightly cocked like a propeller blade.

Picture-winged flies (Delphinia picta)have a peculiar way of sitting at rest with their wings spread out, slightly cocked like a propeller blade.   They are intermediate in size between a fruit fly and a house fly with brown bodies and matching eyes and legs.  The most distinctive thing about them is the strange markings on their spread wings.

A frontal view shows the fly cleaning its proboscis with its front legs.  The black and white pattern on the wings is more clearly visible from this angle.

A frontal view shows the fly cleaning its proboscis with its front legs. The black and white pattern on the wings is more clearly visible from this angle.  Picture-winged?  I don’t see it.

Both larvae and adult Picture-winged Flies are saprophagic, meaning they feed on dead and rotting plant material, especially bulbs of onions, iris, rotting fruit, etc.  In fact, they are most often found near garbage dumps and will lay their eggs right in the rotting vegetation to hatch and complete larval development.  The heat of plant decomposition probably helps speed their development along.  The first batch of larvae to develop in the spring will complete their pupal development to adulthood and start the life cycle over again.  But successive generations of these flies are very photoperiod sensitive, with late summer larvae going into a diapause (like hibernation) for the remainder of the summer and winter, finally completing their pupal development the following spring. Pretty smart for a bug!

6 thoughts on “Odd flies

    • Thanks, Kathy. I have been finding some cool critters in the backyard lately. The birds seem to have deserted me, so I have to focus on the other activities occurring there.

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